There are photoelectric converters, particularly for photovoltaics, including a light-absorbing layer of a Group I-III-VI compound such as CIG or CIGS or a Group I-II-IV-VI compound such as CZTS. Examples of such photoelectric converters are disclosed in Japanese Unexamined Patent Application Publication Nos. 2000-299486 and 2007-269589.
A photoelectric converter including such a light-absorbing layer is composed of a plurality of photoelectric cells arranged side by side in a plane. Each photoelectric cell includes, in sequence on a substrate such as a glass substrate, a lower electrode layer such as a metal electrode, a photoelectric layer composed of layers such as a light-absorbing layer and a buffer layer, and an upper electrode layer such as a transparent electrode or a metal electrode. The photoelectric cells are electrically connected in series such that the upper electrode layer of one photoelectric cell is electrically connected to the lower electrode layer of another photoelectric cell adjacent thereto via a connection conductor.
There is a constant need for an improvement in the photoelectric conversion efficiency of a photoelectric converter. The photoelectric conversion efficiency is the proportion of solar energy converted into electrical energy by the photoelectric converter. For example, the photoelectric conversion efficiency is derived as the electrical energy, produced by the photoelectric converter, divided by the solar energy incident on the photoelectric converter and multiplied by 100.
In view of the foregoing, an object of the present invention is to improve the photoelectric conversion efficiency of a photoelectric converter.